Polypeptide growth factors regulate kidney development, growth, and function and participate in processes of repair after renal injury. The use of one or more growth factors as therapeutic agents has been proposed in the settings of acute and chronic renal failure. In animal models of acute renal injury, the administration of epidermal growth factor, insulin-like growth factor I (IGF-I), or hepatocyte growth factor accelerates the restoration of kidney function and the normalization of histology post-acute renal injury and reduces mortality. The mechanisms by which the growth factors act in acute renal failure include the stimulation of anabolism, the maintenance of glomerular filtration, and the enhancement of tubular regeneration. IGF-I has been safely administered to humans with chronic renal failure. The growth factor enhances GFR and RPF in these individuals. Further studies will be required to establish a role for IGF-I or other growth factors as therapeutic agents for acute renal failure in humans and to define the utility of IGF-I as a medical therapy for chronic renal insufficiency.